In a majority of cases, potentially harmful emissions from incinerators are consequences of upsets in operating conditions, are transient, can vary greatly in composition and amount, and are therefore difficult to completely characterize. Major research needs for improving the reliability and acceptability of incinerators at Superfund sites are therefore a better understanding of the classes of chemicals that can be produced, their toxicity, and for developing a continuous monitor that provides a signal that correlates well with the emissions of potential mutagens. The aims of the proposed project are the characterization of the chemicals formed during the combustion of surrogate wastes, using bacterial and human cell assays to guide the nomination of compounds for more detailed toxicological studies, and the investigation of the use of laser induced fluorescence (LIF) as a continuous monitor. The chemical composition, mutagenicity, and LIF signal of the products of incomplete combustion of liquid droplets burning in both envelope and wake flame modes will be studied. The experimental conditions are selected to generate the classes of compounds produced from droplet combustion burning under diffusion and partially premixed conditions. Preliminary studies have indicated that the principal mutagens produced by combustion, as measured by bacterial cell assays with enzymatic activation, are the polycyclic aromatic hydrocarbons which are readily detected down to the part per billion level by LIF. The major thrusts of this project are therefore to continue the existing study on the identification of compounds in the exhaust of incinerators that are mutagens by the use of bacterial and human cell assays and to evaluate the potential of LIF as continuous stack monitor. An integral part of the study will be to further our understanding of how the composition and mutagenicity of the products of incomplete combustion are influenced by combustion conditions and fuel type. An additional objective is to translate the results from the laboratory to the field by testing the LIF instrument on a 3 MW thermal pilot facility at MIT in year two of the project and in the field in year three.